parser: port test "whitespace fixes"

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

parser_test.zig

@@ -1505,6 +1505,18 @@ test "zig fmt: block in slice expression" {
     );
 }
 
+test "zig fmt: whitespace fixes" {
+    try testTransform("test \"\" {\r\n\tconst hi = x;\r\n}\n// zig fmt: off\ntest \"\"{\r\n\tconst a  = b;}\r\n",
+        \\test "" {
+        \\    const hi = x;
+        \\}
+        \\// zig fmt: off
+        \\test ""{
+        \\    const a  = b;}
+        \\
+    );
+}
+
 test "zig fmt: tagged union with enum values" {
     try testCanonical(
         \\const MultipleChoice2 = union(enum(u32)) {